During polishing of a silicon wafer by chemical mechanical polishing (CMP), a polishing process with multiple steps, such as three or four steps, is performed to achieve high-precision planarization. The slurry used for the last polishing step usually contains a water-soluble polymer such as hydroxyethyl cellulose (HEC) or polyvinyl alcohol (PVA).
For example, JP 2012-216723 A discloses a polishing composition containing at least one water-soluble polymer selected from vinyl alcohol-based resins having a 1,2-diol structural unit, and alkali.